Purified water is used in many applications, including the chemical, power, medical and pharmaceutical industries, as well as for human consumption. Typically, prior to use, water is treated to reduce the level of contaminants to acceptable limits. Treatment techniques include physical processes such as filtration, sedimentation, and distillation; biological processes such as slow sand filters or activated sludge; chemical processes such as flocculation and chlorination; and the use of electromagnetic radiation such as ultraviolet light.
Physical filtration systems are used to separate solids from fluids by interposing a medium (e.g., a mesh or screen) through which only the fluid can pass. Undesirable particles larger than the openings in the mesh or screen are retained while the fluid is purified. In water treatment applications, for example, contaminants from wastewater such as stormwater runoff, sediment, heavy metals, organic compounds, animal waste, and oil and grease must be sufficiently removed prior to reuse.
Traditional continuous loop rotating belt screens and filters often fail in applications of high organic content, specifically fats, oils, and greases. This failure is at least partially due to low motive force cleaning technology that allows the continuous loop screen to become plugged. Without an effective cleaning device, the liquid filtration systems that integrate these filtering screens fail regularly. These technologies are therefore of limited usefulness in applications of high solids greater than 100 mg/l and situations where the solids may be sticky and include fats, oils, and greases.